WO2000059045A2 - Multilayer semiconductor structure with phosphide-passivated germanium substrate - Google Patents

Multilayer semiconductor structure with phosphide-passivated germanium substrate Download PDF

Info

Publication number
WO2000059045A2
WO2000059045A2 PCT/US2000/007402 US0007402W WO0059045A2 WO 2000059045 A2 WO2000059045 A2 WO 2000059045A2 US 0007402 W US0007402 W US 0007402W WO 0059045 A2 WO0059045 A2 WO 0059045A2
Authority
WO
WIPO (PCT)
Prior art keywords
layer
phosphide
germanium
phosphorus
region
Prior art date
Application number
PCT/US2000/007402
Other languages
French (fr)
Other versions
WO2000059045A3 (en
Inventor
James H. Ermer
Li Cai
Moran Haddad
Bruce T. Cavicchi
Nasser H. Karam
Original Assignee
Hughes Electronics Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hughes Electronics Corporation filed Critical Hughes Electronics Corporation
Priority to EP00941106A priority Critical patent/EP1090429B1/en
Priority to DE60033252T priority patent/DE60033252T2/en
Priority to JP2000608449A priority patent/JP3389218B2/en
Publication of WO2000059045A2 publication Critical patent/WO2000059045A2/en
Publication of WO2000059045A3 publication Critical patent/WO2000059045A3/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • H01L31/0687—Multiple junction or tandem solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/26—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, elements provided for in two or more of the groups H01L29/16, H01L29/18, H01L29/20, H01L29/22, H01L29/24, e.g. alloys
    • H01L29/267—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, elements provided for in two or more of the groups H01L29/16, H01L29/18, H01L29/20, H01L29/22, H01L29/24, e.g. alloys in different semiconductor regions, e.g. heterojunctions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/184—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIIBV compounds, e.g. GaAs, InP
    • H01L31/1852—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof the active layers comprising only AIIIBV compounds, e.g. GaAs, InP comprising a growth substrate not being an AIIIBV compound
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/544—Solar cells from Group III-V materials
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This invention relates to multilayer semiconductor structures, and, more particularly, to a solar cell with a phosphide-passivated germanium substrate.
  • a typical solar cell includes two or more layers of semiconductor materials.
  • the materials are chosen such that, when light from the sun falls upon the solar cell, a voltage difference and current result between the layers. Electrical contacts affixed to the external surfaces of the top-most and bottom-most layers collect the current and provide external electrodes through which the useful electrical energy is conveyed.
  • Solar cells are used in a variety of terrestrial and space applications. In terrestrial applications, solar cells are often used in remote locations where it is uneconomical to provide power lines. In space applications, solar cells are used to power many types of satellites, such as communications satellites. The performance and operating efficiency of the solar cells is especially important in the space applications, because of the expense of lifting the solar cells and associated structure to orbit.
  • One well-known type of solar cell uses a homojunction germanium solar cell as the substrate upon which is deposited a gallium arsenide second solar cell.
  • the homojunction within the germanium substrate typically is made by doping the surface region of the germanium substrate with arsenic.
  • the gallium arsenide second solar cell is deposited overlying the doped region, to passivate the germanium and to form the solar cell.
  • the efficiency of such a solar cell may be further improved by adding additional junctions, as by depositing a gallium indium phosphide solar cell overlying the gallium arsenide solar cell.
  • the gallium indium phosphide solar cell converts the shorter wavelengths of solar energy to electrical energy more efficiently. The longer wavelengths pass through the gallium indium phosphide solar cell to the underlying solar cells, where they are converted to electrical energy.
  • the gallium arsenide/germanium and the gallium indium phosphide/gallium arsenide/germanium multijunction solar cells both are operable and achieve good results, but limitations remain.
  • the inventors have recognized that better electrical characteristics could be obtained through better passivation of the germanium surface and shallower doping of the germanium.
  • the present invention fulfills the need for improved electrical properties of solar cells, and particularly multijunction solar cells.
  • the present invention provides a multilayer semiconductor structure.
  • the structure of the invention is useful as an independent solar cell or as the substrate upon which more complex multijunction solar cells are fabricated.
  • the multilayer semiconductor structure is built upon a doped germanium substrate.
  • the approach of the invention allows for better passivation of the germanium homojunction substrate and shallower doping profiles with better control over diffused dopant concentrations. The result is improved electrical characteristics, as compared with existing solar cells.
  • the approach of the invention also allows for better heteroepitaxial nucleation of the overlying layers of added structure on the germanium substrate.
  • a multilayer (i.e., two or more layers) semiconductor structure comprises a germanium substrate having a first surface.
  • the germanium substrate comprises two regions, a bulk germanium region, and a phosphorus-doped germanium region adjacent to the first surface.
  • a layer of a phosphide material overlies and contacts the first surface of the germanium substrate.
  • the phosphide material is gallium indium phosphide, aluminum indium phosphide, or gallium aluminum indium phosphide.
  • a layer of n-type gallium arsenide overlies and contacts the layer of the phosphide material. Electrical contacts may be applied to the phosphide layer or, where present, the n-type gallium arsenide layer, and to the opposite face of the germanium substrate.
  • the bulk germanium region is preferably p-type germanium, and the phosphorus-doped germanium region is preferably n-type germanium.
  • the phosphorus-doped germanium region in conjunction with the bulk germanium region form a homojunction, as required for the solar cell application.
  • the overlying phosphide layer passivates the homojunction, and specifically the phosphorus-doped germanium region. More complex multilayer structures may be deposited on top of the basic single-junction and multijunction solar cells described above.
  • the multilayer semiconductor structure of the invention achieves improved electrical conversion performance as a solar cell, as compared with other structures.
  • Figure 1 is a schematic elevational view of a multilayer semiconductor structure according to the invention.
  • Figure 2 is a schematic elevational view of a multijunction solar cell according to the invention.
  • Figure 3 is a pictorial block flow diagram of an approach for fabricating the solar cell of Figure 2.
  • Figure 4 is a schematic perspective view of a solar panel utilizing a solar cell according to the invention.
  • Figure 1 illustrates a multilayer semiconductor structure 20 according to a preferred embodiment of the invention.
  • the structure 20 includes a germanium substrate 22 having a first surface 24 and a second surface 26.
  • the germanium substrate 22 is preferably from about 25 micrometers (microns) to about 300 micrometers thick, most preferably from about 150 micrometers to about 200 micrometers thick.
  • the germanium substrate 22 has two regions.
  • a bulk germanium region 28 is p-type germanium.
  • the bulk germanium region 28 typically is doped with gallium in a concentration that is preferably from about 5 x 10 i6 atoms per cubic centimeter to about 2 x 10 18 atoms per cubic centimeter, most preferably about 1 x 10 18 atoms per cubic centimeter.
  • a phosphorus-doped germanium region 30 is an uppermost portion of the germanium substrate 22. adjacent to the first surface 24.
  • the phosphorus-doped germanium region 30 has a boundary 32 with the bulk germanium region 28.
  • the phosphorus-doped germanium region 30 is doped with a sufficient concentration of phosphorus to convert the p-type germanium material to n-type germanium.
  • the phosphorus-doped germanium region 30 is preferably from about 0.1 micrometers to about 3.0 micrometers thick, most preferably from about 0.1 micrometers to about 0.5 micrometers thick.
  • the phosphorus-doped germanium region 30 has a gradient in phosphorus concentration from a maximum value at the first surface 24 to a lesser value at the boundary 32.
  • the concentration of the phosphorus in the phosphorus-doped germanium region 30 is from about 1 x 10 17 to about 1 x 10 20 atoms per cubic centimeter, more preferably from about 3 x 10 18 atoms per cubic centimeter to about 3 x 10 i9 atoms per cubic centimeter, and most preferably from about 5 x 10 18 atoms per cubic centimeter to about 1 x 10 19 atoms per cubic centimeter.
  • the two regions 28 and 30 provide a homojunction within the germanium substrate 22, in close proximity to the boundary 32.
  • a layer 34 of a phosphide material overlies and contacts the first surface 24 of the germanium substrate 22.
  • Operable phosphide materials for the layer 34 include, but are not limited to, gallium indium phosphide, aluminum indium phosphide, and gallium aluminum indium phosphide.
  • the thickness of the phosphide layer 34 is preferably from about 25 Angstroms to about 5000 Angstroms, more preferably from about 25 Angstroms to about 1500 Angstroms. even more preferably from about 25 Angstroms to about 500 Angstroms, and most preferably about 100 Angstroms.
  • the composition of the phosphide layer 34 may be selected to provide a desired degree of lattice matching with the underlying n-doped germanium region 30, which is typically close to [001] germanium.
  • gallium indium phosphide is nominally Gag 5 Ino 5 P and aluminum indium phosphide is nominally Al 05 In 05 P.
  • the Ga/In and Al/In ratios may be altered slightly to achieve lattice matching, such as to and [Al b ino 51 ]P, respectively.
  • Gallium aluminum indium phosphide is nominally [GaAl] 0 J I ⁇ Q 5 P, but its elemental ratios may be changed slightly, as for example to [GaAlj ⁇ 49 Ino 5 ,P. Such changes in the elemental ratios alter the lattice parameters of the phosphide material.
  • the lattice parameter of the phosphide layer 34 may be matched, or selectively made non-matching, to the underlying n-doped germanium region 30.
  • the nucleation and growth of layer 34, as well as the overlying layers, on the region 30 is controlled to some extent by the degree of lattice matching.
  • the n-doped germanium region 30 and the phosphide layer 34 while both containing phosphorus, are distinctly different portions of the structure 20.
  • the concentration of phosphorus dopant in the n-doped germanium region 30 is relatively dilute so that the phosphorus is considered a dopant, whereas the concentration of phosphorus in the phosphide layer 34 is relatively high so that the phosphorus is considered a constituent element.
  • a contacting layer 36 of n-type gallium arsenide may be deposited overlying the structure 20.
  • the contacting layer 36 is gallium arsenide doped with a concentration of silicon at 2 x 10 18 atoms per cubic centimeter, and is preferably about 0.5 micrometers thick.
  • Electrical contacts 38 in the form of a metallization layer 38a contacting the second surface 26 and an array of stripes 38b contacting the exposed face of the contacting layer 36 are added.
  • the structure 20 may be used either in stand-alone applications, with the contacting layer 36, or in conjunction with other overlying layers to form a wide variety of devices.
  • the contacting layer may be provided as a layer lying only under the electrical contacts 38b, rather than as a full layer as illustrated in Figure 1.
  • the preferred application is a multijunction solar cell, which is built upon the structure 20. The following discussion describes a preferred multijunction solar cell, but the structure 20 may be used in other applications as well.
  • FIG. 2 depicts a multijunction solar cell 40 comprising the structure 20, as well as additional layers.
  • the above discussion of the structure 20 is incorporated here, and the same reference numerals are used in Figure 2 where applicable.
  • a tunnel junction 42 overlies an upper surface of the contacting layer 36.
  • the tunnel junction 42 is formed of two sublayers, an n-type gallium arsenide layer 42a doped with about 1 x 10 19 to about 1 x 10 20 atoms per cubic centimeter of tellurium that overlies and contacts the contacting layer 36, and a p-type gallium arsenide layer 42b doped with from about 1 x 10 19 to about 5 x 10 20 atoms per cubic centimeter of carbon that overlies and contacts the layer 42a.
  • Each of the layers 42a and 42b is from about 100 to about 900 Angstroms thick.
  • the tunnel junction is essentially transparent to light to permit illumination of the underlying structure 20.
  • a back surface field layer 44 of p-type gallium indium phosphide which is preferably about 1000 Angstroms thick.
  • a layer 46 of p-type gallium arsenide which is preferably from about 1 to about 5 micrometers thick.
  • a layer 48 of n-type gallium arsenide which is preferably from about 500 to about 5000 Angstroms thick.
  • a window layer 50 of n-type gallium indium phosphide which is preferably from about 250 to about 5000 Angstroms thick. The window layer 50 passivates the structure and is resistant to physical damage arising from external sources.
  • Electrode contact to the multijunction solar cell 40 is made through a back surface metallization layer 52 deposited on the second (back) surface 26, and through a series of top surface stripes 54 contacting a top surface 56 of the window layer 50 or a suitable intermediate contacting material overlying the window layer. Solar energy is introduced into the solar cell 40 through the portion of the top surface 56 which is not covered with the electrical contact stripes 54.
  • Other layers and elements may also be provided on the solar cell 40, and the present invention is compatible with the use of such additional layers and elements.
  • Figure 3 illustrates a preferred approach to the fabrication of a multilayer semiconductor structure 20 and a multijunction solar cell 40, as depicted in Figures 1 and 2, respectively.
  • the germanium substrate 22 is furnished, numeral 60.
  • the p-doped germanium substrate material is available commercially.
  • Phosphorus atoms are deposited on the first surface 24 and diffused into the first surface 24 to create the phosphorus-doped germanium region 30, numeral 62.
  • the deposition is preferably accomplished by metal-organic vapor phase epitaxy (MOVPE).
  • MOVPE metal-organic vapor phase epitaxy
  • a commercially available MOVPE apparatus, used by the inventors to make prototype specimens, is an EMCORE E-400 production reactor.
  • the germanium substrate 22 is heated to a temperature of about 580°C-750°C, and phosphine gas introduced to contact the first surface 24.
  • Phosphorus atoms deposited onto the first surface 24 diffuse into the germanium substrate 22, to create the region 30.
  • the introduction and interdiffusion of phosphorus atoms continues during the subsequent deposition of the phosphide layer 34, so that the total time of diffusion of phosphorus into the substrate 22 is about 1 hour but may be adjusted as desired to establish the depth of the n-doped region 30.
  • the use of phosphorus and phosphides allows more shallow doping than in the prior approach of using arsenic and arsenides. This shallow doping is more desirable for the emitter region of the germanium homojunction structure.
  • the phosphide layer 34 is deposited onto the first surface 24, numeral 64.
  • the phosphide layer is preferably deposited by MOVPE.
  • metal organic vapors containing the other elements of the phosphide layer 34 are introduced into the MOVPE apparatus, together with the phosphine gas, to commence step 64.
  • Gases used as sources of the remaining elements of the phosphide layer 34 include, for example, trimethyl gallium or triethyl gallium as a source of gallium, trimethyl or triethyl aluminum as a source of aluminum, and trimethyl indium as a source of indium.
  • the deposition step 64 is continued for as long as required to produce the desired thickness of the phosphide layer 34.
  • the layer 36 of gallium arsenide is deposited onto the layer 34 from a mixture of trimethyl or triethyl gallium and arsine gases.
  • the additional semiconductor layers 42a, 42b, 44, 46, 48, and 50 are deposited in that order, numeral 66, preferably by MOVPE.
  • the structure is cooled to room temperature and removed from the MOVPE apparatus.
  • the electrical contact metallization layer 52 and the stripes 54 are deposited, numeral 68, typically by electron beam vapor deposition, though a mask in the case of the stripes 54.
  • the wafer may thereafter be diced to separate the individual solar cells.
  • Structures 20 were fabricated according to the methods described herein, for gallium indium phosphide layer 34 (24 cells) and aluminum indium phosphide layer 34 (23 cells), and the contacting layer 36.
  • a conventional cell was fabricated with no phosphide layer 34 (1 1 cells), and having only the contacting layer 36 overlying an arsenic-doped germanium substrate. All of the cells were tested under equivalent test conditions.
  • T e gallium indium phosphide cells achieved, on average, an open circuit voltage of 0.213 volts, a short-circuit current of 0.1 17 amperes, and an efficiency of 2.31 percent.
  • the aluminum indium phosphide cells achieved, on average, an open circuit voltage of 0.195 volts, a short-circuit current of 0.1 12 amperes, and an efficiency of 2.13 percent.
  • the conventional cells achieved, on average, an open circuit voltage of 0.204 volts, a short-circuit current of 0.1 10 amperes, and an efficiency of 1.95 percent.
  • two or more of the individual solar cells made according to the approach of the invention may be assembled together and electrically interconnected to form a solar panel 100.
  • the solar panel 100 includes a sufficient number of individual solar cells 102, such as the solar cells 40 of Figure 2 or other solar cells employing the approach of the invention, appropriately interconnected to provide the desired voltage and current outputs.
  • the individual solar cells 102 are mounted to a support base 104 and electrically interconnected by appropriate wiring 106 to a controller (not shown).

Abstract

A multilayer semiconductor structure includes a germanium substrate having a first surface. The germanium substrate has two regions, a bulk p-type germanium region, and a phosphorus-doped n-type germanium region adjacent to the first surface. A layer of a phosphide material overlies and contacts the first surface of the germanium substrate. A layer of gallium arsenide overlies and contacts the layer of the phosphide material, and electrical contacts may be added to form a solar cell. Additional photovoltaic junctions may be added to form multijunction solar cells. The solar cells may be assembled together to form solar panels.

Description

MULTILAYER SEMICONDUCTOR STRUCTURE WITH PHOSPHIDE-PAS SIVATED GERMANIUM SUBSTRATE
BACKGROUND OF THE INVENTION
This invention was made with government support under Contract No. F33615-95-C-5561 awarded by the US Air Force. The government has certain rights in this invention.
This invention relates to multilayer semiconductor structures, and, more particularly, to a solar cell with a phosphide-passivated germanium substrate.
A typical solar cell includes two or more layers of semiconductor materials. The materials are chosen such that, when light from the sun falls upon the solar cell, a voltage difference and current result between the layers. Electrical contacts affixed to the external surfaces of the top-most and bottom-most layers collect the current and provide external electrodes through which the useful electrical energy is conveyed. Solar cells are used in a variety of terrestrial and space applications. In terrestrial applications, solar cells are often used in remote locations where it is uneconomical to provide power lines. In space applications, solar cells are used to power many types of satellites, such as communications satellites. The performance and operating efficiency of the solar cells is especially important in the space applications, because of the expense of lifting the solar cells and associated structure to orbit.
One well-known type of solar cell uses a homojunction germanium solar cell as the substrate upon which is deposited a gallium arsenide second solar cell. The homojunction within the germanium substrate typically is made by doping the surface region of the germanium substrate with arsenic. The gallium arsenide second solar cell is deposited overlying the doped region, to passivate the germanium and to form the solar cell. The efficiency of such a solar cell may be further improved by adding additional junctions, as by depositing a gallium indium phosphide solar cell overlying the gallium arsenide solar cell. The gallium indium phosphide solar cell converts the shorter wavelengths of solar energy to electrical energy more efficiently. The longer wavelengths pass through the gallium indium phosphide solar cell to the underlying solar cells, where they are converted to electrical energy.
The gallium arsenide/germanium and the gallium indium phosphide/gallium arsenide/germanium multijunction solar cells both are operable and achieve good results, but limitations remain. The inventors have recognized that better electrical characteristics could be obtained through better passivation of the germanium surface and shallower doping of the germanium. The present invention fulfills the need for improved electrical properties of solar cells, and particularly multijunction solar cells.
SUMMARY OF THE INVENTION
The present invention provides a multilayer semiconductor structure. The structure of the invention is useful as an independent solar cell or as the substrate upon which more complex multijunction solar cells are fabricated. The multilayer semiconductor structure is built upon a doped germanium substrate. The approach of the invention allows for better passivation of the germanium homojunction substrate and shallower doping profiles with better control over diffused dopant concentrations. The result is improved electrical characteristics, as compared with existing solar cells. The approach of the invention also allows for better heteroepitaxial nucleation of the overlying layers of added structure on the germanium substrate.
In accordance with the invention, a multilayer (i.e., two or more layers) semiconductor structure comprises a germanium substrate having a first surface. The germanium substrate comprises two regions, a bulk germanium region, and a phosphorus-doped germanium region adjacent to the first surface. A layer of a phosphide material overlies and contacts the first surface of the germanium substrate. Preferably, the phosphide material is gallium indium phosphide, aluminum indium phosphide, or gallium aluminum indium phosphide. In a preferred embodiment, a layer of n-type gallium arsenide overlies and contacts the layer of the phosphide material. Electrical contacts may be applied to the phosphide layer or, where present, the n-type gallium arsenide layer, and to the opposite face of the germanium substrate.
The bulk germanium region is preferably p-type germanium, and the phosphorus-doped germanium region is preferably n-type germanium. The phosphorus-doped germanium region in conjunction with the bulk germanium region form a homojunction, as required for the solar cell application. The overlying phosphide layer passivates the homojunction, and specifically the phosphorus-doped germanium region. More complex multilayer structures may be deposited on top of the basic single-junction and multijunction solar cells described above.
The multilayer semiconductor structure of the invention achieves improved electrical conversion performance as a solar cell, as compared with other structures. Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic elevational view of a multilayer semiconductor structure according to the invention;
Figure 2 is a schematic elevational view of a multijunction solar cell according to the invention;
Figure 3 is a pictorial block flow diagram of an approach for fabricating the solar cell of Figure 2; and
Figure 4 is a schematic perspective view of a solar panel utilizing a solar cell according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 illustrates a multilayer semiconductor structure 20 according to a preferred embodiment of the invention. (As in the other drawings herein. Figure 1 is not drawn to scale.) The structure 20 includes a germanium substrate 22 having a first surface 24 and a second surface 26. The germanium substrate 22 is preferably from about 25 micrometers (microns) to about 300 micrometers thick, most preferably from about 150 micrometers to about 200 micrometers thick. The germanium substrate 22 has two regions. A bulk germanium region 28 is p-type germanium. The bulk germanium region 28 typically is doped with gallium in a concentration that is preferably from about 5 x 10i6 atoms per cubic centimeter to about 2 x 1018 atoms per cubic centimeter, most preferably about 1 x 1018 atoms per cubic centimeter.
A phosphorus-doped germanium region 30 is an uppermost portion of the germanium substrate 22. adjacent to the first surface 24. The phosphorus-doped germanium region 30 has a boundary 32 with the bulk germanium region 28. The phosphorus-doped germanium region 30 is doped with a sufficient concentration of phosphorus to convert the p-type germanium material to n-type germanium. The phosphorus-doped germanium region 30 is preferably from about 0.1 micrometers to about 3.0 micrometers thick, most preferably from about 0.1 micrometers to about 0.5 micrometers thick. The phosphorus-doped germanium region 30 has a gradient in phosphorus concentration from a maximum value at the first surface 24 to a lesser value at the boundary 32. On average through the region 30, the concentration of the phosphorus in the phosphorus-doped germanium region 30 is from about 1 x 1017 to about 1 x 1020 atoms per cubic centimeter, more preferably from about 3 x 1018 atoms per cubic centimeter to about 3 x 10i9 atoms per cubic centimeter, and most preferably from about 5 x 1018 atoms per cubic centimeter to about 1 x 1019 atoms per cubic centimeter. The two regions 28 and 30 provide a homojunction within the germanium substrate 22, in close proximity to the boundary 32.
A layer 34 of a phosphide material overlies and contacts the first surface 24 of the germanium substrate 22. Operable phosphide materials for the layer 34 include, but are not limited to, gallium indium phosphide, aluminum indium phosphide, and gallium aluminum indium phosphide. The thickness of the phosphide layer 34 is preferably from about 25 Angstroms to about 5000 Angstroms, more preferably from about 25 Angstroms to about 1500 Angstroms. even more preferably from about 25 Angstroms to about 500 Angstroms, and most preferably about 100 Angstroms.
The composition of the phosphide layer 34 may be selected to provide a desired degree of lattice matching with the underlying n-doped germanium region 30, which is typically close to [001] germanium. To cite examples, gallium indium phosphide is nominally Gag 5Ino 5P and aluminum indium phosphide is nominally Al05In05P. The Ga/In and Al/In ratios may be altered slightly to achieve lattice matching, such as to
Figure imgf000007_0001
and [Albino 51]P, respectively. Gallium aluminum indium phosphide is nominally [GaAl]0 JIΠQ 5P, but its elemental ratios may be changed slightly, as for example to [GaAlj^ 49Ino 5 ,P. Such changes in the elemental ratios alter the lattice parameters of the phosphide material. By selection of the elemental ratios, the lattice parameter of the phosphide layer 34 may be matched, or selectively made non-matching, to the underlying n-doped germanium region 30. The nucleation and growth of layer 34, as well as the overlying layers, on the region 30 is controlled to some extent by the degree of lattice matching. Absent the phosphide layer and its several degrees of freedom in adjusting the elemental ratios and therefore the lattice constant, there is substantially less control over the nucleation and growth of any overlying layers, such as will be described subsequently. The n-doped germanium region 30 and the phosphide layer 34, while both containing phosphorus, are distinctly different portions of the structure 20. The concentration of phosphorus dopant in the n-doped germanium region 30 is relatively dilute so that the phosphorus is considered a dopant, whereas the concentration of phosphorus in the phosphide layer 34 is relatively high so that the phosphorus is considered a constituent element.
To form a solar cell, a contacting layer 36 of n-type gallium arsenide may be deposited overlying the structure 20. The contacting layer 36 is gallium arsenide doped with a concentration of silicon at 2 x 1018 atoms per cubic centimeter, and is preferably about 0.5 micrometers thick. Electrical contacts 38 in the form of a metallization layer 38a contacting the second surface 26 and an array of stripes 38b contacting the exposed face of the contacting layer 36 are added.
The structure 20 may be used either in stand-alone applications, with the contacting layer 36, or in conjunction with other overlying layers to form a wide variety of devices. (In stand-alone applications, the contacting layer may be provided as a layer lying only under the electrical contacts 38b, rather than as a full layer as illustrated in Figure 1.) The preferred application is a multijunction solar cell, which is built upon the structure 20. The following discussion describes a preferred multijunction solar cell, but the structure 20 may be used in other applications as well.
Figure 2 depicts a multijunction solar cell 40 comprising the structure 20, as well as additional layers. The above discussion of the structure 20 is incorporated here, and the same reference numerals are used in Figure 2 where applicable.
In the solar cell 40, a tunnel junction 42 overlies an upper surface of the contacting layer 36. The tunnel junction 42 is formed of two sublayers, an n-type gallium arsenide layer 42a doped with about 1 x 1019 to about 1 x 1020 atoms per cubic centimeter of tellurium that overlies and contacts the contacting layer 36, and a p-type gallium arsenide layer 42b doped with from about 1 x 1019 to about 5 x 1020 atoms per cubic centimeter of carbon that overlies and contacts the layer 42a. Each of the layers 42a and 42b is from about 100 to about 900 Angstroms thick. The tunnel junction is essentially transparent to light to permit illumination of the underlying structure 20.
Overlying and contacting the tunnel junction 42. is a back surface field layer 44 of p-type gallium indium phosphide, which is preferably about 1000 Angstroms thick. Overlying and contacting the back surface field layer 44 is a layer 46 of p-type gallium arsenide, which is preferably from about 1 to about 5 micrometers thick. Overlying and contacting the layer 46 is a layer 48 of n-type gallium arsenide, which is preferably from about 500 to about 5000 Angstroms thick. Overlying and contacting the layer 46 is a window layer 50 of n-type gallium indium phosphide, which is preferably from about 250 to about 5000 Angstroms thick. The window layer 50 passivates the structure and is resistant to physical damage arising from external sources.
Electrical contact to the multijunction solar cell 40 is made through a back surface metallization layer 52 deposited on the second (back) surface 26, and through a series of top surface stripes 54 contacting a top surface 56 of the window layer 50 or a suitable intermediate contacting material overlying the window layer. Solar energy is introduced into the solar cell 40 through the portion of the top surface 56 which is not covered with the electrical contact stripes 54. Other layers and elements may also be provided on the solar cell 40, and the present invention is compatible with the use of such additional layers and elements.
Figure 3 illustrates a preferred approach to the fabrication of a multilayer semiconductor structure 20 and a multijunction solar cell 40, as depicted in Figures 1 and 2, respectively. The germanium substrate 22 is furnished, numeral 60. The p-doped germanium substrate material is available commercially.
Phosphorus atoms are deposited on the first surface 24 and diffused into the first surface 24 to create the phosphorus-doped germanium region 30, numeral 62. The deposition is preferably accomplished by metal-organic vapor phase epitaxy (MOVPE). A commercially available MOVPE apparatus, used by the inventors to make prototype specimens, is an EMCORE E-400 production reactor. In the preferred approach, the germanium substrate 22 is heated to a temperature of about 580°C-750°C, and phosphine gas introduced to contact the first surface 24. Phosphorus atoms deposited onto the first surface 24 diffuse into the germanium substrate 22, to create the region 30. The introduction and interdiffusion of phosphorus atoms continues during the subsequent deposition of the phosphide layer 34, so that the total time of diffusion of phosphorus into the substrate 22 is about 1 hour but may be adjusted as desired to establish the depth of the n-doped region 30. The use of phosphorus and phosphides allows more shallow doping than in the prior approach of using arsenic and arsenides. This shallow doping is more desirable for the emitter region of the germanium homojunction structure.
The phosphide layer 34 is deposited onto the first surface 24, numeral 64. The phosphide layer is preferably deposited by MOVPE. After the step 62 has continued for a sufficient period of time to diffuse the desired phosphorus atoms, metal organic vapors containing the other elements of the phosphide layer 34 are introduced into the MOVPE apparatus, together with the phosphine gas, to commence step 64. Gases used as sources of the remaining elements of the phosphide layer 34 include, for example, trimethyl gallium or triethyl gallium as a source of gallium, trimethyl or triethyl aluminum as a source of aluminum, and trimethyl indium as a source of indium. Other organic and inorganic gases may be introduced as sources for other elements, such as dopants of the layer 34, if desired. The deposition step 64 is continued for as long as required to produce the desired thickness of the phosphide layer 34. The layer 36 of gallium arsenide is deposited onto the layer 34 from a mixture of trimethyl or triethyl gallium and arsine gases.
At this point, fabrication of the multilayer semiconductor structure 20 is complete.
To fabricate the multijunction solar cell 40, the additional semiconductor layers 42a, 42b, 44, 46, 48, and 50 are deposited in that order, numeral 66, preferably by MOVPE. After the deposition step 66 is completed, the structure is cooled to room temperature and removed from the MOVPE apparatus. The electrical contact metallization layer 52 and the stripes 54 are deposited, numeral 68, typically by electron beam vapor deposition, though a mask in the case of the stripes 54.
If more than one solar cell is fabricated at a time on a large substrate, as would usually be the case in a production operation, the wafer may thereafter be diced to separate the individual solar cells.
Structures 20 were fabricated according to the methods described herein, for gallium indium phosphide layer 34 (24 cells) and aluminum indium phosphide layer 34 (23 cells), and the contacting layer 36. For comparison, a conventional cell was fabricated with no phosphide layer 34 (1 1 cells), and having only the contacting layer 36 overlying an arsenic-doped germanium substrate. All of the cells were tested under equivalent test conditions. T e gallium indium phosphide cells achieved, on average, an open circuit voltage of 0.213 volts, a short-circuit current of 0.1 17 amperes, and an efficiency of 2.31 percent. The aluminum indium phosphide cells achieved, on average, an open circuit voltage of 0.195 volts, a short-circuit current of 0.1 12 amperes, and an efficiency of 2.13 percent.
The conventional cells achieved, on average, an open circuit voltage of 0.204 volts, a short-circuit current of 0.1 10 amperes, and an efficiency of 1.95 percent.
As shown in Figure 4, two or more of the individual solar cells made according to the approach of the invention may be assembled together and electrically interconnected to form a solar panel 100. The solar panel 100 includes a sufficient number of individual solar cells 102, such as the solar cells 40 of Figure 2 or other solar cells employing the approach of the invention, appropriately interconnected to provide the desired voltage and current outputs. The individual solar cells 102 are mounted to a support base 104 and electrically interconnected by appropriate wiring 106 to a controller (not shown).
Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.
Accordingly, the invention is not to be limited except as by the appended claims.

Claims

CLAIMSWhat is claimed is:
1. A multilayer semiconductor structure, comprising: a germanium substrate having a first surface, the germanium substrate comprising two regions, a bulk germanium region, and a phosphorus-doped germanium region adj acent to the first surface; and a layer of a phosphide material overlying and contacting the first surface of the germanium substrate.
2. The structure of claim 1, further including a layer of gallium arsenide overlying and contacting the layer of the phosphide material.
3. The structure of claim 1, wherein the layer of the phosphide material comprises a material selected from the group consisting of gallium indium phosphide, aluminum indium phosphide, and gallium aluminum indium phosphide.
4. The structure of claim 1. wherein the bulk germanium region is p- type germanium.
5. The structure of claim 1. wherein the phosphorus-doped germanium region is n-type germanium.
6. The structure of claim 1. wherein the phosphorus-doped germanium region extends inwardly from the first surface toward the germanium region for a distance of from about 0.1 to about 3.0 micrometers.
7. The structure of claim 1. wherein the phosphorus-doped region has an average phosphorus content of from about 1 x 1017 to about 1 x 1020 atoms per cubic centimeter.
8. The structure of claim 1. wherein the layer of the phosphide material has a thickness of from about 25 to about 5000 Angstroms.
9. The structure of claim 2, further including a first electrical contact to the bulk germanium region, and a second electrical contact to the layer of gallium arsenide.
10. The structure of claim 1, further including at least one additional solar cell junction overlying the layer of a phosphide material.
11. A multilayer semiconductor structure, comprising: a germanium substrate having a first surface, the germanium substrate comprising two regions, a bulk p-type germanium region, and a phosphorus-doped n-type germanium region adjacent to the first surface; a layer of a phosphide material overlying and contacting the first surface of the germanium substrate; and a layer of gallium arsenide overlying and contacting the layer of the phosphide material.
12. The structure of claim 1 1 , wherein the layer of the phosphide material comprises a material selected from the group consisting of gallium indium phosphide, aluminum indium phosphide, and gallium aluminum indium phosphide.
13. The structure of claim 1 1. wherein the phosphorus-doped germanium region extends inwardly from the first surface toward the germanium region for a distance of about 0.1 to about 3.0 micrometers.
14. The structure of claim 11 , wherein the phosphorus-doped region has an average phosphorus content of from about 1 x 1017 to about 1 x 1020 atoms per cubic centimeter.
15. The structure of claim 11, wherein the layer of the phosphide material has a thickness of from about 25 to about 5000 Angstroms.
16. The structure of claim 11, further including a first electrical contact to the bulk germanium region, and a second electrical contact to the layer of gallium arsenide.
17. A solar panel comprising at least two solar cells, each solar cell having a structure comprising a germanium substrate having a first surface, the germanium substrate comprising two regions, a bulk germanium region, and a phosphorus-doped germanium region adjacent to the first surface; and a layer of a phosphide material overlying and contacting the first surface of the germanium substrate.
18. The solar panel of claim 17, further including at least one additional solar cell junction overlying the layer of a phosphide material in each of the solar cells.
19. The solar panel of claim 17, wherein the layer of the phosphide material of each of the solar cells comprises a material selected from the group consisting of gallium indium phosphide, aluminum indium phosphide, and gallium aluminum indium phosphide.
20. The solar panel of claim 17. further including a support base to which the solar cells are mounted.
21. A method of making a multilayer semiconductor structure, comprising the steps of furnishing a germanium substrate having a first surface; thereafter diffusing phosphorus into the first surface of the substrate; and depositing a layer of a phosphide overlying and in contact with the first surface.
22. The method of claim 21. including a further step, after the step of depositing a layer of a phosphide, of depositing a layer of gallium arsenide overlying and in contact with the layer of a phosphide.
PCT/US2000/007402 1999-03-29 2000-03-20 Multilayer semiconductor structure with phosphide-passivated germanium substrate WO2000059045A2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP00941106A EP1090429B1 (en) 1999-03-29 2000-03-20 Multilayer semiconductor structure with phosphide-passivated germanium substrate
DE60033252T DE60033252T2 (en) 1999-03-29 2000-03-20 MULTILAYER SEMICONDUCTOR STRUCTURE WITH PHOSPHIDE-PASSIVATED GERMANIUM SUBSTRATE
JP2000608449A JP3389218B2 (en) 1999-03-29 2000-03-20 Multilayer semiconductor structure with phosphide passivated germanium substrate

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/280,771 1999-03-29
US09/280,771 US6380601B1 (en) 1999-03-29 1999-03-29 Multilayer semiconductor structure with phosphide-passivated germanium substrate

Publications (2)

Publication Number Publication Date
WO2000059045A2 true WO2000059045A2 (en) 2000-10-05
WO2000059045A3 WO2000059045A3 (en) 2001-01-04

Family

ID=23074569

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/007402 WO2000059045A2 (en) 1999-03-29 2000-03-20 Multilayer semiconductor structure with phosphide-passivated germanium substrate

Country Status (5)

Country Link
US (1) US6380601B1 (en)
EP (1) EP1090429B1 (en)
JP (1) JP3389218B2 (en)
DE (1) DE60033252T2 (en)
WO (1) WO2000059045A2 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008017143A1 (en) 2006-08-11 2008-02-14 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group iv substrate with controlled interface properties and diffusion tails
US7553691B2 (en) 2002-10-31 2009-06-30 Emcore Solar Power, Inc. Method and apparatus of multiplejunction solar cell structure with high band gap heterojunction middle cell
US8362460B2 (en) 2006-08-11 2013-01-29 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group IV substrate with controlled interface properties and diffusion tails
US10367107B2 (en) 2011-08-29 2019-07-30 Iqe Plc Multijunction photovoltaic device having an Si barrier between cells

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7339109B2 (en) * 2000-06-20 2008-03-04 Emcore Corporation Apparatus and method for optimizing the efficiency of germanium junctions in multi-junction solar cells
US7151307B2 (en) * 2001-05-08 2006-12-19 The Boeing Company Integrated semiconductor circuits on photo-active Germanium substrates
US6787818B2 (en) * 2001-10-12 2004-09-07 The Boeing Company Diffused junction photodetector and fabrication technique
US7560750B2 (en) * 2003-06-26 2009-07-14 Kyocera Corporation Solar cell device
US7052587B2 (en) * 2003-06-27 2006-05-30 General Motors Corporation Photoelectrochemical device and electrode
US20050059186A1 (en) * 2003-09-15 2005-03-17 Kelly Nelson A. Photoelectrochemical device and method of making
US7422966B2 (en) 2005-05-05 2008-09-09 Micron Technology, Inc. Technique for passivation of germanium
US10069026B2 (en) 2005-12-19 2018-09-04 The Boeing Company Reduced band gap absorber for solar cells
US20070262296A1 (en) * 2006-05-11 2007-11-15 Matthias Bauer Photodetectors employing germanium layers
US20080110489A1 (en) * 2006-11-14 2008-05-15 Fareed Sepehry-Fard Very High Efficiency Multi-Junction Solar Spectrum Integrator Cells, and the Corresponding System and Method
GB2467935B (en) 2009-02-19 2013-10-30 Iqe Silicon Compounds Ltd Formation of thin layers of GaAs and germanium materials
GB2467934B (en) 2009-02-19 2013-10-30 Iqe Silicon Compounds Ltd Photovoltaic cell
US8852994B2 (en) 2010-05-24 2014-10-07 Masimo Semiconductor, Inc. Method of fabricating bifacial tandem solar cells
US20120273042A1 (en) * 2011-04-29 2012-11-01 Xing-Quan Liu Method for improving the quality of a tunnel junction in a solar cell structure
TWI521600B (en) 2011-06-03 2016-02-11 應用材料股份有限公司 Method of forming high growth rate, low resistivity germanium film on silicon substrate(1)
US20180053874A1 (en) 2016-08-19 2018-02-22 Solar Junction Corporation Dilute nitride devices with active group iv substrate and controlled dopant diffusion at the nucleation layer-substrate interface
US10593818B2 (en) 2016-12-09 2020-03-17 The Boeing Company Multijunction solar cell having patterned emitter and method of making the solar cell
WO2019010037A1 (en) 2017-07-06 2019-01-10 Solar Junction Corporation Hybrid mocvd/mbe epitaxial growth of high-efficiency lattice-matched multijunction solar cells
WO2019161128A1 (en) 2018-02-15 2019-08-22 Solar Junction Corporation High-temperature semiconductor barrier regions
WO2020033706A1 (en) 2018-08-09 2020-02-13 Array Photonics, Inc. Hydrogen diffusion barrier for hybrid semiconductor growth
US10964835B2 (en) * 2018-08-29 2021-03-30 The Boeing Company Universal broadband photodetector design and fabrication process

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0447327A2 (en) * 1990-03-15 1991-09-18 Fujitsu Limited Heterostructure semiconductor device
US5405453A (en) * 1993-11-08 1995-04-11 Applied Solar Energy Corporation High efficiency multi-junction solar cell

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4207670A (en) * 1978-09-28 1980-06-17 General Electric Company Method for making a solid state neuron
US5342453A (en) * 1992-11-13 1994-08-30 Midwest Research Institute Heterojunction solar cell
US5376185A (en) * 1993-05-12 1994-12-27 Midwest Research Institute Single-junction solar cells with the optimum band gap for terrestrial concentrator applications
US5853497A (en) * 1996-12-12 1998-12-29 Hughes Electronics Corporation High efficiency multi-junction solar cells
US5911839A (en) * 1996-12-16 1999-06-15 National Science Council Of Republic Of China High efficiency GaInP NIP solar cells

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0447327A2 (en) * 1990-03-15 1991-09-18 Fujitsu Limited Heterostructure semiconductor device
US5405453A (en) * 1993-11-08 1995-04-11 Applied Solar Energy Corporation High efficiency multi-junction solar cell

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
CHIANG P K ET AL: "LARGE AREA GAInP2/GAAS/GE MULTIJUNCTION SOLAR CELLS FOR SPACE APPLICATIONS" WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY,US,NEW YORK, IEEE, vol. CONF. 1, 5 December 1994 (1994-12-05), pages 2120-2123, XP000680195 ISBN: 0-7803-1460-3 *
MASAFUMI YAMAGUCHI: "COMPOUND SEMICONDUCTOR SOLAR CELLS, PRESENT STATUS" OPTOELECTRONICS DEVICES AND TECHNOLOGIES,JP,MITA PRESS, TOKYO, vol. 5, no. 2, 1 December 1990 (1990-12-01), pages 143-155, XP000264379 ISSN: 0912-5434 *
WEINBERG I ET AL: "SHORT COMMUNICATION: HETEROEPITAXIAL INP SOLAR CELLS FOR SPACE APPLICATIONS" PROGRESS IN PHOTOVOLTAICS. RESEARCH AND APPLICATIONS,GB,JOHN WILEY AND SONS, CHICHESTER, vol. 1, no. 1, 1993, pages 43-45, XP000365272 ISSN: 1062-7995 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7553691B2 (en) 2002-10-31 2009-06-30 Emcore Solar Power, Inc. Method and apparatus of multiplejunction solar cell structure with high band gap heterojunction middle cell
US7709287B2 (en) 2002-10-31 2010-05-04 Emcore Solar Power, Inc. Method of forming a multijunction solar cell structure with a GaAs/AIGaAs tunnel diode
WO2008017143A1 (en) 2006-08-11 2008-02-14 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group iv substrate with controlled interface properties and diffusion tails
EP2050124A1 (en) * 2006-08-11 2009-04-22 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group iv substrate with controlled interface properties and diffusion tails
EP2050124A4 (en) * 2006-08-11 2009-10-21 Cyrium Technologies Inc Method of fabricating semiconductor devices on a group iv substrate with controlled interface properties and diffusion tails
US8124958B2 (en) 2006-08-11 2012-02-28 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group IV substrate with controlled interface properties and diffusion tails
EP2428981A1 (en) * 2006-08-11 2012-03-14 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group iv substrate with controlled interface properties and diffusion tails
US8362460B2 (en) 2006-08-11 2013-01-29 Cyrium Technologies Incorporated Method of fabricating semiconductor devices on a group IV substrate with controlled interface properties and diffusion tails
US10367107B2 (en) 2011-08-29 2019-07-30 Iqe Plc Multijunction photovoltaic device having an Si barrier between cells

Also Published As

Publication number Publication date
EP1090429A2 (en) 2001-04-11
WO2000059045A3 (en) 2001-01-04
JP3389218B2 (en) 2003-03-24
EP1090429B1 (en) 2007-02-07
JP2002540635A (en) 2002-11-26
DE60033252D1 (en) 2007-03-22
DE60033252T2 (en) 2007-08-30
US6380601B1 (en) 2002-04-30

Similar Documents

Publication Publication Date Title
US6380601B1 (en) Multilayer semiconductor structure with phosphide-passivated germanium substrate
US10367107B2 (en) Multijunction photovoltaic device having an Si barrier between cells
US7122733B2 (en) Multi-junction photovoltaic cell having buffer layers for the growth of single crystal boron compounds
US5944913A (en) High-efficiency solar cell and method for fabrication
CA1207422A (en) Three-terminal ternary iii-v multicolor solar cells and process of fabrication
US6504091B2 (en) Photoelectric converting device
EP1231648B1 (en) Solar cell and manufacturing method thereof
US7339109B2 (en) Apparatus and method for optimizing the efficiency of germanium junctions in multi-junction solar cells
US7217882B2 (en) Broad spectrum solar cell
US4404421A (en) Ternary III-V multicolor solar cells and process of fabrication
US4400221A (en) Fabrication of gallium arsenide-germanium heteroface junction device
US7309832B2 (en) Multi-junction solar cell device
US4385198A (en) Gallium arsenide-germanium heteroface junction device
US4575577A (en) Ternary III-V multicolor solar cells containing a quaternary window layer and a quaternary transition layer
WO1995013626A1 (en) High efficiency solar cell
TWI647736B (en) Dilute nitride devices with active group iv substrate and controlled dopant diffusion at the nucleation layer-substrate interface
WO1990009039A1 (en) High efficiency solar cell
EP0817279A1 (en) Process for the production of a chalcopyrite structure semiconductor thin film containing a specific dopant
Beeler et al. Band gap-engineered group-IV optoelectronic semiconductors, photodiodes and prototype photovoltaic devices
CN112119506A (en) High temperature semiconductor barrier region
WO2003052836A1 (en) Multi-junction solar cell device
Lewis et al. The compositional grading of MOCVD-grown GaAs 1− x P x via substrate temperature changes

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): JP

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2000941106

Country of ref document: EP

AK Designated states

Kind code of ref document: A3

Designated state(s): JP

AL Designated countries for regional patents

Kind code of ref document: A3

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

WWP Wipo information: published in national office

Ref document number: 2000941106

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 2000941106

Country of ref document: EP